Chemistry
by Rettabold
Summary: Sherlock comes back from the dead to find someone else in his apartment, who doesn't seem to mind him reading her and even does the same in exchange. Mature rating, just in case. OC/Sherlock.
1. Prologue

**Authors Note: So, this is my first time in years writing any sort of fan fiction. I'm not great with grammar or spelling, but i try my best and if you see any mistakes let me know. :) I also wouldn't mind any constructive criticism. Thank you and enjoy. **

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Sherlock sat on a plain stool in the middle of what could be called a living room. He had been staying in a small building, If you could call it a building, more like a shack. Then again, one doesn't need much space when laying low. He didn't have long though, before he could come out and prove to the world that Moriarty was real, and that he was no fraud. He tossed and old newspaper of to the side, the title announcing his apparent suicide. Soon he wouldn't be alone anymore._ Alone_. So strange how he felt the need for human companionship, for his _friends_. Friends he hadn't seen in almost 2 years now. He smiled a little when he thought of them. How John alone had changed him more than he had realized until that day on the roof. Would he have sacrificed himself for anyone else before John had come along? No. He had never cared about anyone enough, At least he never realized it.

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**Some Time Later**

"What do you _mean_ you rented out _my_ apartment to someone else?" Sherlock said in an irritated tone. He had been back for less than a day and he was ready to head upstairs to 221B, after scaring Mrs. Hudson half to death. She stopped him after he was about to leap up the stairs, saying in a soft tone that she had rented it out already. "John, how could you let this happen?! My experiments! My Equipment!" He shook his head in frustration. "Well you couldn't expect us to keep it all, and you know very well couldn't afford it on my own." John piped in. "We thought you were _dead,_ Sherlock. We didn't think you would need it then." John rubbed his forehead as Mrs. Hudson said something about almost having a heart attack he gave her a fright so bad. "Oh, your heart if fine!" Sherlock almost snarled. He then lit up with an idea and turned to go up the stairs. "Now what!" John called after him. "Don't you bother my new tenant Mister Holmes!" Mrs. Hudson shouted as she followed. "I wouldn't dream of it." he smirked briefly, "I just want to say hello." he said before knocking twice on the door, before placing both hands clasped together behind his back.


	2. Someone Knew

**Note: I don't own anything Sherlock. Only the character Claire.**

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A petite woman answered the door with a short "hello" while Sherlock quickly scanned over her. She had short messy hair as if she had just tousled it with a towel. It was a chestnut-brown color, darker at the roots and lighter as it reached the tips. she couldn't have been taller than 5'6'' and skinny, but not in an unhealthy, or lanky way. she wore loose army green khaki pants that rested low on her hips and a loose tank top, both covered in bits of paint most dry and starting to flake from time, while a few strokes where still damp and recent. Her skin was pale with the same paint smudges over her arms. her face was fresh and clean of makeup with light freckles dotted across her nose that matched the brown speckles in her otherwise clear blue eyes.

"Yes, hello." Sherlock started as John sighed "Leave the girl alone, Sherlock. Sorry." he looked up at her apologetically. "It's quite alright, would you like to come in?" She moved out of the way and opened the door for them to fit through. As soon as they were in Sherlock started up again "You don't suppose you are going to move out any time soon?" he scanned the room as he spoke The furniture was all the same and the yellow smiley face still on the wall. It looked very much the same as it did last he saw. Papers were strewn across the tables and there was art supplies scattered throughout the room.

"Sorry about the mess." she said, shrugging off his question. "Sherlock, you can't just ask people to leave because you want it back." John sighed again. "It's alright." she smiled. "Would you like some tea?" it was a rhetorical question as she was already on her way to the kitchen. "I'm sorry I couldn't keep the severed head in the fridge." She called out. She had moved in only about 3 months after his "death" and told Mrs. Hudson that she didn't mind it as it was, though some things John and Mrs. Hudson donated to school science labs, before she even got there. She came out with the tea and set it on the coffee table. "I did keep the skull though." She paused and looked at it. "He isn't much of a conversationalist, though, is he?" She looked back at Sherlock and smiled. "On the contrary, he speaks volumes to me." Sherlock shot back. She was teasing him now. "So, Mr. Holmes, " She paused as she sat down. "We know you aren't dead," she smiled "but can you prove you aren't a fraud?" he scowled briefly at this as John rubbed his head and looked at his friend hoping he wouldn't startup, only to be quickly let down.

"You are Irish originally, but moved to London some years ago, 10 years? A painter, but that doesn't make much money so you would have a flatmate, but a flatmate would never let you keep it this messy for long, and there are no signs of anyone else living here. No, you have another job. Waiting tables, by the way you brought the tray out. your hair is darker at the root than near the tips, could be dye, but no, its natural. Sun-bleached, suggesting that you've been out of the country, but not for some time now. Six months ago was it? " This was less a question and more of a statement.

"You moved in here not long after my "Death" based on the amount of my things still lying around and you don't get attached to where you live as you can see from the lack of many of the things permanent tenants tend to keep. Would you mind moving out?" He looked up at her as John chimed in "Sherlock! you can't just reclaim it like that. It's her place now!" Sherlock gave him look that said he didn't seem to see a problem with that. She grinned and placed her tea on the table gently. "I suppose you can have it back." she paused as John nearly choked on his tea. "You were right, I am unattached. Plus, i have my eye on the basement apartment here, i love a good fixer upper." John glanced between Sherlock and her in confusion. "I'm sorry, did i miss something?" he asked as Sherlock rose to his feet obviously pleased. "Nothing at all, Mr. Watson." She got up and opened the door. "Now, i am running late for work. You may come back later after I've moved out my things." Sherlock got up and moved to the door, but paused before exiting. "How much did i get right?" he asked quietly. "Maybe I'll let you know later." She winked "Oh, and my name is Claire." She said just as she closed the door.

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As John and Sherlock walked down the stairs John spoke, "well, uh... i suppose you could stay with me for a while.. until she moves out. What went on back there anyways? " He stopped briefly to look at his fiend. "i knew the moment she opened the door that she wouldn't stay long. " Sherlock said a bit smugly. "how could you possibly know that from one small glance? " they were outside now, walking along the sidewalk. "Her face showed recognition which isn't surprising since i was all over the newspaper 2 years ago, and she probably knew i used to live there, but the biggest thing was that she didn't look surprised. If you saw a man who was known to the world to be dead at you flat door you would be surprised. You _were_ surprised." He added as he began to hail a cab. "This plus she barely had any possessions of her own and most of my things were exactly where we left them leads me to believe that she was saving it for us.." he was trailing of now as the cab pulled up. "My question is why? How did she know I wasn't dead?" They got in and John just watched as Sherlock thought on this. He was intrigued and he hoped this new mystery wouldn't leave him bored in the end.


	3. Strange Likeness

**Authors Note: I had a bit of trouble with this one, and was hoping to make it a bit longer but i got everything i wanted in the chapter here so i think its alright that its shorter than the last. ) I'm hoping as i get used to writing more and such that my chapters will be longer. ****Let me know what you think. :**

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Molly_ stood over the table with Sherlocks still body laying on top of it. His face was badly damaged and he had a few broken bones, but for survival reasons he would have to push through the pain, for now. On the table next to his was another body, this one dead. The male corpse had similar curly black hair and his face was bashed in even more so than Sherlocks. They were the same height and were both tall and thin. She revived him and he was groggy at first but then shot up, wincing at the pain. His mind was suddenly clear "Clothes." he said shortly. They didn't have much time so he needed to hurry, and to blend in easily. "Everything is set then? his voice was low and she nodded quickly while showing him a back way out. He limped over as she whispered "good luck, Sherlock." He smiled sadly and left saying "Thank you, Molly Hopper."_

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"Are you sure you want to take the basement dear?" Mrs. Hudson and Claire were chatting in the kitchen of 221B. "I am definitely sure, Mrs. Hudson. I like the space, and i enjoy a bit of hard work." she smiled as she poured tea into her mug. "Well it will be a lot cheaper than up here, so maybe you wont have to wait tables as often and get back to your artwork." Mrs. Hudson enjoyed Claires painting and often came upstairs to see her work. There was a clap and they both looked up to see Sherlock in the living room "Sherlock, you can't just come in without permission." John scolded, but of course Sherlock wasn't listening. "All set?" he asked. "I don't have much, just the suitcase and the art supplies by the door. Would you mind helping me take it down to the basement?" she asked with a smile. "We would love to." John smiled picking up one of her portfolios and a box. "So, John are you going to be moving back in, or staying in your current flat?" she was trying to make conversation as they made their way downstairs. "Of course he is." Sherlock responded for him. John sighed but agreed, "My flat is alright, but i suppose Sherlock would get lonely without me." he teased his friend.

All three were in the living room now, and Claire looked around once more to make sure she got all her paints. "Well, i think that's it. Thanks for the help guys." she smiled and turned to the door but Sherlock spoke. "Wait, you still need to tell me what you got right." She grinned and turned to the couch. "Alright then, I am Irish, but that isn't hard to notice, what is impressive is how you can tell how long i've been living here. You were close, it was 12 years." She crossed her legs and began to relax. "I'm an artist, not just a painter, and i do make good money. I just don't make enough for this place." she said gesturing to the apartment. " My hair is natural." She added at the end. "If you can't afford it, why pick it?" Sherlock asked. "I liked it too much." her answer was simple, but there was something hidden underneath that Sherlock couldn't quite read.

"Now, Mr. Holmes"  
"Sherlock." He interrupted. "Sherlock, then. Since you have had the pleasure of figuring me out, I might try my hand at figuring you out." She put her hand on her chin and scrunched her eyebrows together as if thinking hard. "extremely intelligent, obviously, but you can't empathize with other, or at least have trouble with it. You are stubborn and get bored easily. You choose to push away emotions because you feel they get in the way and you have little respect for authority. Bullied as a child because you were _different,_ smarter than the other kids, You don't have many friends and even though you may not admit it, you care very much for them. Enough to die, or at least pretend to, to save their lives." She smiles "I really could go on, but i think ill leave it at that." Sherlock face said he was annoyed, but interested in her. Trying to read more about her. It proved to be harder than he had thought.

As he thought she began to speak again, "although impressive that you can make deductions _almost_ flawlessly, It doesn't prove that you didn't hire Richard Brooke... but of course you wouldn't have come back if you couldn't do just that. So tell me, how will you?" she finished. "Why should i let you know." Sherlock was annoyed with her. "Have i hit a nerve?" she asked faux innocently. John and Sherlocks response was mingled together, a 'yes' from John and a 'no' from Sherlock. Sherlock shot him a look. "You don't have to tell me. I probably already know." she smiled and got up. "I have work to do anyways." She smiled at John and nodded towards Sherlock "Good day." she spoke before leaving.

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Sherlock held in his hand a thick envelope and stood in the office of DI Lestrade. They had only just moments ago entered the office and now were giving Lestrade time to let it all sink in. "Lestrade, I know it may be strange to see me standing here-" Sherlock started, "Bloody right its strange! Sherlock, you were dead!" Sherlock rubbed his forehead and spoke quickly. "Yes. Yes. I _know _that. That's not important. What is important is how i can prove that Moriarty was real!"


	4. Welcome Home

_He sat on the edge of one of the plush chairs that resided in 221B. He wore his nicest clothes and a grim face. It had been about a week, John had lost count of the days and he had finally decided to move out. The site of the flat caused him to much pain. He only needed a few things before he left it for god knows how long. He didn't know if he would ever be able to come back. He played those horrible moments over and over in his head, becoming angry and depressed. What could he have done to prevent this. _Why_ did he do it? John had so many questions unanswered by his friend. He began to fidget with the hat kn his hand and tears began to well up in his eyes but he wouldn't allow them to spill. instead he shook his head and cleared his throat as if to brush off the pain. God, he was so_ mad_ at him for leaving like this. He slammed his fist on the table, " Dammit Sherlock, don't be dead." she said with a frog in his throat. John would never admit it to anyone but Sherlock meant more to him than anyone else in his life. He had been so alone and Sherlock gave him what he needed. There was too much he wished he could say to him. So much, he would never have dreamed of speaking to his face but somehow wished he had. Mrs. Hudson entered the room and spoke gently, "are you ready dear?" Her eyes were a bit puffy and she sniffled a little after the words left her lips. John nodded slowly and made his way to the door, wrapping his arm around Mrs. Hudson to comfort her. When they got to the cemetery there were only a few people there. Not surprising, he didn't have many friends. Molly, Lestrade and Mycroft all stood standing in black. The ceremony was brief and quiet and as soon as everyone had turned away after quiet goodbyes John stepped close to the tombstone and placed a single item atop it. A Deerstalker hat._

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John an Sherlock sat in the Inspectors office. He had just spent most of the night explaining what he had done the past two years. Collecting information. He had found out that he was just one of the many people in a network of criminals. He also found out that they weren't just regular criminals. They had dozens of false identities and high-end facilities. In his research he gained a list of names which he had in his stack of papers on Lestrades desk. The list contained a few big name criminals and grunt workers. Lestrade rubbed his forehead, taking in all the information laying in front of him. "I recognize some of these names. they've been in some of our more recent cases." He said pointing at the list. "Then you have even more proof." Lestrade nodded, "Well we have proof that Richard Brooke was a real man," he paused and looked at John. "They pulled his body out of the river a few months back, But if you look at his identification he shows a great resemblance to Moriarty. Turns out he murdered him just to use his identity as a background. Unlucky face to have i guess." John nodded and Sherlock stood. "Well, if we are done here." He gave a quick smile, that didn't seem sincere and started for the door. "Hold on a minute," Lestrade stopped him. "You still have to explain what happened before.. before you jumped." John nodded at this, "You haven't told anyone what happened up there." John tried his hardest to be patient but he waited long enough to know what happened. Why he jumped and left everyone to mourn him. Sherlock sighed and clasped his hands behind his back before stepping towards the desk again. "Fine. Might as well say it while you are both here, so i don't have to tell it twice. Moriarty gave me a choice: Die, or save my... friends.." he said the word like it made him uncomfortable. "Molly, Uh, helped me. I knew there was a risk, but i tried to break the fall as best i could. " he paused, " Obviously it worked." he said somewhat smugly. "Wait. You mean Molly knew? All this time she knew you were alive?" John was a bit shocked. "Well of course. She is my most trusted... friend." There was that word again. "Plus i knew Moriarty would never think using her against me." He added at the end. Lestrade got up from his desk. He was a bit stunned to hear Sherlock use the word friend _Twice. _Especially when talking about him, he didn't even know his first name 5 years into knowing each other, why would he be considered a friend. "Well this has been an eventful... and interesting evening." He opened the door for them to exit. "I think we have enough for now." he nodded as the two other men exited the office. "Oh, and Sherlock?" Lestrade called after him. "Yes?" he turned his head towards Lestrade. "Welcome back."

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The air was thick with the smell of mildew as Claire scrapped the walls of her newest apartment. She had been working on it all day but as she stepped back to examine the room it seemed as if barely anything had gotten done. The room was bare a lone couch sat in the middle of the living room and a thick layer of dust covered its overstuffed cushions. Her belongings consisted of a suitcase, art supplies and a blanket. She sighed as she went over to pick it up feeling how thin it was before dropping it down. It was getting chilly already and Claire hadn't thought it would take this long to get the room decent enough to stay in. As she kicked herself for not preparing a place to stay, she walked up the stairs to 221B and knocked lightly on the door. John opened the door with a smile. "Oh, hello Claire." he said cheerfully as he invited her in. She stepped though the door. "Hey, uh, i know we don't know each other very well, but i forgot to find a place to stay while i fixed up the basement. Can i stay here?" she asked a little embarrassed. "Only for a day or two, so i can put a new heater in and find a mattress at least. I don't want to intrude..." She started but john added. "sure you can stay." He smiled politely. She looked around the flat and asked, "you don't think Sherlock will mind at all?" John nodded, "He probably will, but that's ok, you can just ignore it." She smiled at that and sat down. "Would you like tea?" he asked. "Sherlock will be out for a while. He is on one of his walks." She nodded and curled her feet under her as she warmed in the cozy apartment.

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The next morning She woke to the sound of annoyance "What is she ding here?" Sherlock asked Watson, who was reading the paper. "Good morning to you too. were you out all night?" John folded the paper up and set it on the table. He had spent a good part of the night chatting with Claire but they went to bed before he saw whether Sherlock came home or not. "Yes. That doesn't answer my question. Why is she on our couch?" John shook his head at his friend. "Make a deduction" He teased before explaining. "She didn't have a place to stay and her apartment is too cold. i let her stay here." He shrugged and made his way to the living room. "Good morning." he smiled at Claire when he saw her awake. "Morning." She nodded sleepily. "How did you sleep?" the question was directed at Sherlock and he responded with a simple "I didn't" before going over to johns computer. "When can we get a case. I'm bored." He was getting annoyed with how much they had to stay put since he got back. "Sherlock, it has only been three days. Be patient." John said as he put on his coat. "Patience isn't my strongest suit. Where are you going?" Sherlock spoke without looking up. "I have things to do today. You two play nice." He said before closing the door. Claire sat up straight and watched Sherlock as he typed, soon though he paused and looked at Claire. "What?" he said simply. "Oh, nothing. I just like watching you." She smiled. "Not in a creepy way." she added quickly. "Why would that be creepy?" he asked, though it was more of a statement. She shook her head, "no reason." She got up walking over to him. "Do you mind if i use your shower?" She asked but he seemed to be in his own place when he nodded yes and waved her off. She made her way down the steps and grabbed a few of her things before heading to her neighbors shower. Afterwards she dressed in a simple pair of jeans and a black V-neck t-shirt. She tousled her hair and let it lay as it was before walking out to the living room. Sherlock sat in the same spot, back leaned against the chair and he looked like he was deep in thought. "You know, I can see you care." she started awkwardly. He looked up at her with a somewhat confused expression on his face. She started up again, "What i mean is. You worry about him. You worry that you put him through too much with your suicide." she spoke softly and he seemed to get uncomfortable with how personal she had become. "I don't mean to pry, but it is ok to have feelings." she sad in the chair near his desk. "Feelings cause problems. Sentiment." he stated simply. "yes, they do, but that doesn't mean you don't have them. I can read them all over your face." she stopped and stood up again. "You wont be able to hide them from me, Sherlock. I'll read them in every expression, and in every word you say. I can see right through you, Just like you can me." With that she left the flat, leaving Sherlock to think on what she said. He didn't like it at all, having someone see his weaknesses.

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Another one done. :) I have so much planned. :D as always, I love a good review. :)


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